Wow, I did not know that, and I just looked it up to confirm. I'm pretty sure I have seen this in the employee manual at every place I've worked since graduating. (I always read them, a depressing venture.) Apparently, the penalty for violating the law is negligible compared to the fear of sharing it puts into employees. The protection also does not appear to extend to "supervisors", so maybe that's how they slip it in. (I'm also not a lawyer, though.)

Thanks for posting those articles -- they're super helpful for others. When I headed up Career Development I strove to create an environment of transparency. That meant we didn't allow pay secrecy policies in our employee manual and trained managers not to imply it. While the penalty is negligible, I always urge companies not to go down the pay secrecy route -- it erodes trust and often leads to higher rates of people leaving (driving down retention).